I have several listboxes in 1 page and there is a "search" button.Whenever user select any values from the listbox's and click search button the query fires and it is showing the desired results.But I want 2 more button on this page "save Query" and "Load Query".
Requirment is:
After selecting values from listboxes before pressing "search" button user should click "Save Query" button for saving his selected values and then he should press search button.Now when the user log in next time if he clicks "Load Query" Button he can see his selected values that he had selected last time.
Actually my application runs on windows authentication.No login user id password is nesessary.So there is no database fields for that.
I want to store listbox selected item in cookies.
Right Now the value is saving in the Cookies but only the last selected value.Please see in my No:2 section for the code that I wrote.

I Tried my code like this but facing some problem:

1)After saving the values if I close the application and again come back to that particular page the values is not selected......
I am writing this code in a click event of a button.
string val=Request.Cookies["toton"].Value;
if(val != null)
{
ListBox1.SelectedValue=val;
}

It is throwing error:Object reference not set to an instance of an object.
System.NullReferenceException.

2)I have several listBoxes.But in cookies it is always saving the last listbox value.Not all the selected value.
I am using this code:


Here always ListBox2.SelectedItem.Text is saving in Cookies.

3)There are 10 ListBoxes in that page.Its not mandetory user will select all the List Boxes.
So if in any situation user is selecting 4 of them,those all 4 values should be saved in cookies and in next login those 4 should be selected.

Can anyBody help me in this regards......